Five Things a CWI Should Know about Coatings

The rise in value-added services has reshaped how inspection companies market themselves. Companies often promote the idea of the dual-certified inspector — someone to cover both welding and coatings. The idea seems efficient: one well-rounded professional who can streamline oversight, reduce labor costs, and deliver more-thorough inspections. But behind that convenience lies a tougher reality for welding inspectors. Many are not offered hands-on training but are suddenly expected to step into a role with extra responsibilities. Here are five things a welding inspector should know about coatings.

1. Know industry standards and specifications. Many surface preparation and coatings standards referenced in job specifications are published by the Association for Materials Protection and Performance (AMPP, formerly NACE and SSPC), ASTM International, and the International Organization for Standardization (ISO). Certified Welding Inspectors (CWIs) stepping into the inspection of coatings should become familiar with these organizations’ publications since their standards define surface cleanliness, surface profile, coating thickness measurement, and inspection procedures.

2. Surface preparation is critical. Poor surface preparation is the leading cause of premature coating failure. Inspectors should verify cleanliness and surface profile before painting. Tools include replica tape and micrometers for nondigital verification or digital depth micrometers for faster measurements. Visual standards such as SSPC-VIS 1, Guide and Reference Photographs for Steel Surfaces Prepared by Dry Abrasive Blast Cleaning, provide side-by-side comparisons to confirm the required level of preparation.

3. Monitor environmental conditions. Every coating’s chemistry reacts differently to its surroundings during application and curing. The ambient temperature, wet bulb temperature, humidity, dew point, and substrate surface temperature must be measured before and during coating. Digital dew point meters with surface temperature probes simplify this process, while a sling psychrometer (with psychrometric charts) and a surface temperature gauge remain reliable nondigital options. These readings confirm whether conditions meet the coating manufacturer’s requirements.

4. Check the application and thickness. Each coat of paint has a purpose and recommended thickness. Inspectors should evaluate the application for discontinuities, which can compromise performance. The dry film thickness (DFT) is measured per SSPC-PA 2, Procedure for Determining Conformance to Dry Coating Thickness Requirements, to verify that results fall within specification. Electronic DFT gauges are the most common choice, while nonelectronic gauges are less expensive and less accurate. Use certified coated standards to verify instrument accuracy.

5. Observe and document. Document environmental conditions, coating batch numbers, expiration dates, surface preparation times, application times, inspection results, and nonconformances.

Basic coatings awareness can make a significant difference even without a full coatings certification. CWIs who juggle both roles often switch between two sets of standards, equipment, terminology, and procedures. Yet this additional work is frequently overlooked in project planning and employee compensation. For those thrown into coatings without much preparation, starting with the fundamentals can make the work more manageable.

LUCY DRAUS (ldraus@drausinspection.com) is the owner of Draus Inspection, Conneaut Lake, Pa. She is an AWS CWI and AMPP Senior Certified Coatings Inspector.